Associative Array ?
Array with key and value pairs is known as associative array.
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Number of ways to define array in php?

// 1st way
$arr = array(1,2,4,5,6,7);

// 2nd way
$arr = array(
        'lucknow',
        'patna',
        'kanpur',
        'noida'
      );

// 3rd way
$arr = ['lucknow','patna','kanpur'];

// 4th way
$arr[] = 'lucknow';
$arr[] = 'kanpur';
$arr[] = 'patna';
$arr[] = 'noida';

// Difference between print_r() and var_export()

var_export() print output array so that we can use that array as it is in our php code.

If we didn't define key of any array then it will take automatically an auto-incremented integer as a key.
(key starts from INT 0)

NOTE : Next key will be last "maximum INT value of key" + 1

